This invention relates to a chemical vapor deposition apparatus and to a method of clearing material from between an inner wall of a chemical vapor deposition chamber and an outer surface of a chamber liner.
A chemical vapor deposition apparatus generally includes a chemical vapor processing chamber which is required to be as free as possible of contaminant gases and material (hereinafter generally referred to as "contaminants"). However, it is sometimes required that a component be positioned within the processing chamber so as to line an inner wall thereof, resulting in a volume or an interface, between the inner wall and the component, in which contaminant material collects.
For example, FIG. 1 of the accompanying drawings illustrates a conventional chemical vapor deposition apparatus 10 which includes a chemical vapor deposition processing chamber 12, equipment 14 for handling a wafer within the processing chamber 12, and lamps 16 located above and below the processing chamber 12.
The processing chamber 12 includes a stainless steel base ring 18, and upper and lower quartz windows 20 and 22, respectively sealing circumferentially within opposing sides of the base ring 18. An upper quartz liner ring 24 and a lower quartz liner ring 26 are located within the processing chamber 12. The upper liner ring 24 lines an upper part of the base ring 18 and a portion of the upper window 20, and the lower liner ring 26 lines a lower portion of the base ring 18 and a portion of the lower window 22. The purpose of the liner rings 24 and 26 is to protect the base ring from exposure to process gasses and severe temperature conditions within the processing chamber 12.
Processing gas inlet and outlet ports 28 and 30 are provided in opposing walls of the base ring 18. Processing gas inlet and outlet recesses, 32 and 34 respectively, are cut into sections of the circumference of the lower liner ring 26, thereby placing the inlet and outlet ports 28 and 30 in communication with the processing environment of the processing chamber 12.
During processing, a wafer is held in position by the equipment 14 and heated to a required temperature by the lamps 16. Process gas is then introduced into the processing chamber 12 through the inlet port 28 and allowed to react and form a deposited layer on the wafer. Replacement gas is then introduced through the inlet port 28 so that the process gas and any reaction byproducts are discharged through the outlet port 30.
The chemical vapor deposition apparatus 10 per se is known in the art and is therefore not further elaborated on herein. Suffice to say that it is required for the processing environment within the processing chamber 12 to be as free as possible of contaminants. However, it has been found that contaminants accumulate in spaces on an interface 36 between the base ring 18 and the lower quartz liner ring 26. It is known that these contaminants include iron oxide, resulting from oxidation and chemical deterioration of the base ring 18, chemical vapor deposition byproduct gases and materials, such as chlorine, and water.
FIG. 2 is a sectioned side view on 2--2 of FIG. 1, illustrating only the processing chamber 12. A slit 38 is formed through the base ring 18 and the lower liner ring 26, which is used for inserting wafers into and removing wafers from the processing chamber 12, and a thermocouple port 40 is formed through the base ring 18 and an interface between the upper liner ring 24 and the lower liner ring 26. The thermocouple port 40 is used for temperature calibration and is thereafter closed off be means of a plug 42.
FIGS. 3 and 4 illustrate the lower liner ring 26 from opposing sides, i.e. rotated through 180.degree., showing the process gas inlet and outlet recesses, 32 and 34 respectively, the thermocouple port 40 and the slit 38, as they are visible on the lower liner ring 26.